In the field of a magnetic recording medium, Patent Literature 1 discloses a technique for measuring the respective thicknesses of a first layer on a base film and a second layer above the base film. This technique includes causing two kinds of light having respective center wavelengths different from each other to be transmitted through a magnetic recording medium including a base film, a first layer, and a second layer to calculate the respective thicknesses of the first layer and the second layer from the respective intensities of the two kinds of transmitted light.